Effects Of Preharvest And Postharvest Melatonin Application On The Fruit Quality Of Strawberry

Strawberry(Fragaria × ananassa Duch.)is a herb belonging to the Rosaceae genus.It originated in Europe and was first introduced into China as an ornamental plant.It is widely cultivated because of its bright color,sweet and sour taste,and rich nutrition.China’s strawberry consumption is mainly based on fresh sales.However,due to the short maturation period,concentrated listing,high water content(90-95%),and delicate organization,it is vulnerable to external physical,chemical and biological factors and causes quality deterioration.Loss of commerciality.As consumers pay more and more attention to the nutritional quality of fruit and the practical problems of short shelf life of strawberry fruits,improving strawberry fruit quality and exploring effective storage and preservation methods are the key to further improve the economic benefits of strawberries.In this paper,melatonin was used to treat strawberry fruits.The Effects of Pre-harvest and Post-harvest 300 (?)M,500 (?)M and 700 (?)M melatonin on the quality of strawberry fruits were studied.The results showed that there was no significant difference in single fruit weight,transverse diameter,color,soluble solids,total phenolics and total flavonoids in the fruit weight,transverse diameter,color,total phenolics and total flavonoids in the mature strawberry fruit with 300 (?)M melatonin in the light green period,the white ripening period and the beginning of the red period,and the spraying 500 and 700 (?)M melatonin respectively in the light green period and the white ripening period could significantly increase the maturity of the ripe strawberry fruit.The contents of fruit weight,transverse diameter,color,soluble solid,total phenol and total flavonoids significantly decreased the content of Vc in fruit,and the fruit weight,vertical diameter,color,soluble solid,Vc,total phenol and total flavonoids in ripe strawberry fruits were significantly increased after 500 (?)M and 700(?)M melatonin respectively.The results showed that the effect of spraying 500 (?)M and700 (?)M melatonin on the fruit quality in the light green period of strawberry fruit development,white ripening period and the beginning of red period increased the fruit quality significantly,and the effect of spraying 500 (?)M melatonin in the beginning of red period was the best.Compared with the control,the storage period of strawberry fruits was prolonged by 1,1 and 5 days respectively after Post-harvest spraying 300 (?)M,500 (?)M and 700(?)M of melatonin respectively.In addition,there was no significant difference in fruit hardness,soluble solids,Vc,total phenolics and total flavonoids by spraying 300 (?)M melatonin,and 500 (?)M and 700 (?)M melatonin could significantly delay the contents of strawberry fruit hardness,soluble solids,Vc,total phenol and total flavonoids in the storage process.Reducing the antioxidant capacity of strawberry fruit during storage,in addition to the hardness,500 (?)M treatment can better maintain the content of SSC,anthocyanin,Vc,total phenol,total flavonoids and the antioxidant capacity of fruit during the storage of strawberry fruit,but the content of titratable acid in the storage process of fruit is not certain,but the content of titratable acid in the storage process of fruit is not necessarily the same.It can play a positive effect.The results showed that spraying 300 (?)M,500 (?)M and 700 (?)M melatonin could prolong the storage period of the fruit,and both 500 (?)M and 700 (?)M could effectively maintain the fruit quality in the storage period,especially with 500 (?)M melatonin treatment.Further antagonism of oxidase SOD,POD,CAT and APX activity showed that the activity of POD and CAT enzyme in strawberry fruit increased gradually with the storage time,and the activity of SOD and APX enzyme decreased gradually.The viability of the fruits treated with 300 (?)M,500 (?)M and 700 (?)M melatonin were significantly higher than those of the control,of which the effect of 500 (?)M and 700(?)M was better.There was no significant difference in the activity of APX between the3 treatments.The results showed that 300 (?)M,500 (?)M and 700 (?)M melatonin had a positive effect on the activity of SOD,POD and CAT enzyme in strawberry fruit,of which 500 (?)M and 700 (?)M treatment were better than the control group and 300 M treatment.Although 300 (?)M treatment kept the antioxidant enzyme activity of strawberry fruit to some extent,but the activity of antioxidant enzyme was maintained to a certain extent.The results are poor compared with the 500 (?)M and 700 (?)M treatments.Meanwhile,melatonin treatment had no significant effect on APX activity in strawberry fruits during storage.It can be found that Pre-harvest spraying exogenous melatonin can improve the appearance quality and nutritional quality of fruit during the first red period,while exogenous melatonin can significantly reduce the decay rate of strawberry during storage and prolong the storage period of fruit.In the beginning of the red period,500(?)M treatment was the best to improve the quality of fruit;Post-harvest,the best treatment was 500 (?)M,and it had better practical application value.